The invention relates to a bridge crane comprising at least one main girder, a trolley moving on the main girder or at least one hoist gear fixed to the main girder, end carriages arranged at the ends of the main girder to support the main girder, wheels arranged to the end carriages intended to move along substantially parallel rails substantially parallel to the end carriages and on the other hand substantially transverse in relation to the main girder and thus to support the entire crane on said rails, while slide means have been arranged between one end carriage and the corresponding end of the main girder allowing a longitudinal movement of said end carriage in relation to the main girder and a rotation of said end carriage and main girder in relation to each other, and stop means have been arranged between the main girder and the end carriage to restrict the movement between the end carriage and main girder.
It is very common for bridge cranes to have the following problematic conditions and situations: either one or both rails may be bent and thus at the limits of the allowed tolerances or in excess thereof. The rail track may be indeterminate or variable, especially on tracks located outdoors or on tracks arranged in halls with a flexible framework. The rail track of a crane may change due to changes in temperature, especially in cranes located outdoors. The crane may also have to be built in conditions where the direction of all rail wheels cannot be guaranteed to be within tolerances.
When using current bridge cranes, the movement of the crane may be difficult due to the above-mentioned reasons while the wear of the wheels and rails is heavy. To eliminate problems caused by the rails, the requirements for accuracy of manufacture of a crane have to be kept high, which raises the costs considerably. In addition, specific problems are caused by the drive means of the crane and their different controls which affect the directness of crane movement in different situations. In such cases, deflected movement may cause extensive problems.